A conventional article of athletic footwear includes two primary elements, an upper and a sole structure. The upper provides a covering for the foot that securely receives and positions the foot with respect to the sole structure. The sole structure is secured to a lower portion of the upper and is positioned between the foot and the ground. In addition to attenuating ground reaction forces, the sole structure may provide traction and control foot motions. The upper and the sole structure operate cooperatively to provide a comfortable structure that is suited for a variety of ambulatory activities, such as walking and running.
The sole structure of athletic footwear generally exhibits a layered configuration that may include a comfort-enhancing insole, a resilient midsole, and a ground-contacting outsole that provides both abrasion-resistance and traction. The insole is a thin, compressible member located within the upper and adjacent to a plantar (i.e., lower) surface of the foot to enhance footwear comfort. The midsole is generally the primary sole structure element that attenuates ground reaction forces and controls foot motions. Polymer foam materials suitable for the midsole include ethylvinylacetate or polyurethane, which compress resiliently under an applied load to attenuate ground reaction forces created by the impacts of running and jumping. In addition to polymer foam materials, midsoles may include, for example, one or more fluid-filled bladders and other impact-attenuating devices. The outsole forms the ground-contacting element of footwear and is usually fashioned from a durable, wear-resistant material, such as a carbon-black rubber compound, that may include texturing to improve traction.
Certain articles of footwear have midsole assemblies that include a top layer and a midsole assembly formed of a plurality of support elements. For example, an article of footwear, commercially manufactured and distributed by NIKE, Inc. under the SHOX trademark, includes a midsole having a top layer made of a conventional impact force attenuating material and a midsole assembly. The midsole assembly in at least some of these articles of footwear includes a top plate, a bottom plate and a plurality of support elements disposed between the top plate and the bottom plate. Examples of such midsole assemblies can be found in the disclosures of U.S. Pat. No. 6,964,120, entitled “Footwear Midsole with Compressible Element in Lateral Heel Area,” issued to Cartier et al. on Nov. 15, 2005, and U.S. Pat. No. 7,314,125, entitled “Impact Attenuating and Spring Elements and Products Containing Such Elements,” issued to Smaldone et al. on Jan. 1, 2008, each of these patents being incorporated by reference herein in their entireties.
The sole provides a multiplicity of utilitarian functions, but it may also serve to personalize the article of footwear. Thus, applying brand information, colors, decorations, etc. to the soles of footwear may be desirable. A variety of techniques for creating decorated soles have been developed.
For example, a sole element comprised of three layers—a chassis, a transparent skin, and a film having a color and/or design sandwiched therebetween—is disclosed in U.S. Pat. No. 7,089,691. It is disclosed that the chassis and the skin are integrally formed (via “reverse injection” or “dual injection”) and that all three layers are able to chemically bond to one another.
As another example, a sole element is formed by liquid molding a sole composition to a printed membrane laminate is disclosed in U.S. Patent Publication No. 2004/0216331. The membrane laminate is formed by printing colors onto a polymeric porous membrane and subsequently laminating a protective layer over the printing to protect the printing and make it waterproof.
Many of the graphics that result from these methods of decorating the soles of footwear are of questionable durability, of questionable graphic quality, or both. It would be desirable to incorporate durable graphics of photographic quality into the sole of an article of footwear. Accordingly, it would be desirable to provide high-quality decorated midsoles for footwear that are easy to produce and that can withstand the wear and tear associated with the soles of articles of footwear.